1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * BCM947xx nvram variable access 4 * 5 * Copyright (C) 2005 Broadcom Corporation 6 * Copyright (C) 2006 Felix Fietkau <nbd@openwrt.org> 7 * Copyright (C) 2010-2012 Hauke Mehrtens <hauke@hauke-m.de> 8 */ 9 10 #include <linux/io.h> 11 #include <linux/types.h> 12 #include <linux/module.h> 13 #include <linux/kernel.h> 14 #include <linux/string.h> 15 #include <linux/mtd/mtd.h> 16 #include <linux/bcm47xx_nvram.h> 17 18 #define NVRAM_MAGIC 0x48534C46 /* 'FLSH' */ 19 #define NVRAM_SPACE 0x10000 20 #define NVRAM_MAX_GPIO_ENTRIES 32 21 #define NVRAM_MAX_GPIO_VALUE_LEN 30 22 23 #define FLASH_MIN 0x00020000 /* Minimum flash size */ 24 25 struct nvram_header { 26 u32 magic; 27 u32 len; 28 u32 crc_ver_init; /* 0:7 crc, 8:15 ver, 16:31 sdram_init */ 29 u32 config_refresh; /* 0:15 sdram_config, 16:31 sdram_refresh */ 30 u32 config_ncdl; /* ncdl values for memc */ 31 }; 32 33 static char nvram_buf[NVRAM_SPACE]; 34 static size_t nvram_len; 35 static const u32 nvram_sizes[] = {0x6000, 0x8000, 0xF000, 0x10000}; 36 37 static u32 find_nvram_size(void __iomem *end) 38 { 39 struct nvram_header __iomem *header; 40 int i; 41 42 for (i = 0; i < ARRAY_SIZE(nvram_sizes); i++) { 43 header = (struct nvram_header *)(end - nvram_sizes[i]); 44 if (header->magic == NVRAM_MAGIC) 45 return nvram_sizes[i]; 46 } 47 48 return 0; 49 } 50 51 /* Probe for NVRAM header */ 52 static int nvram_find_and_copy(void __iomem *iobase, u32 lim) 53 { 54 struct nvram_header __iomem *header; 55 u32 off; 56 u32 size; 57 58 if (nvram_len) { 59 pr_warn("nvram already initialized\n"); 60 return -EEXIST; 61 } 62 63 /* TODO: when nvram is on nand flash check for bad blocks first. */ 64 off = FLASH_MIN; 65 while (off <= lim) { 66 /* Windowed flash access */ 67 size = find_nvram_size(iobase + off); 68 if (size) { 69 header = (struct nvram_header *)(iobase + off - size); 70 goto found; 71 } 72 off <<= 1; 73 } 74 75 /* Try embedded NVRAM at 4 KB and 1 KB as last resorts */ 76 header = (struct nvram_header *)(iobase + 4096); 77 if (header->magic == NVRAM_MAGIC) { 78 size = NVRAM_SPACE; 79 goto found; 80 } 81 82 header = (struct nvram_header *)(iobase + 1024); 83 if (header->magic == NVRAM_MAGIC) { 84 size = NVRAM_SPACE; 85 goto found; 86 } 87 88 pr_err("no nvram found\n"); 89 return -ENXIO; 90 91 found: 92 __ioread32_copy(nvram_buf, header, sizeof(*header) / 4); 93 nvram_len = ((struct nvram_header *)(nvram_buf))->len; 94 if (nvram_len > size) { 95 pr_err("The nvram size according to the header seems to be bigger than the partition on flash\n"); 96 nvram_len = size; 97 } 98 if (nvram_len >= NVRAM_SPACE) { 99 pr_err("nvram on flash (%i bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n", 100 nvram_len, NVRAM_SPACE - 1); 101 nvram_len = NVRAM_SPACE - 1; 102 } 103 /* proceed reading data after header */ 104 __ioread32_copy(nvram_buf + sizeof(*header), header + 1, 105 DIV_ROUND_UP(nvram_len, 4)); 106 nvram_buf[NVRAM_SPACE - 1] = '\0'; 107 108 return 0; 109 } 110 111 /* 112 * On bcm47xx we need access to the NVRAM very early, so we can't use mtd 113 * subsystem to access flash. We can't even use platform device / driver to 114 * store memory offset. 115 * To handle this we provide following symbol. It's supposed to be called as 116 * soon as we get info about flash device, before any NVRAM entry is needed. 117 */ 118 int bcm47xx_nvram_init_from_mem(u32 base, u32 lim) 119 { 120 void __iomem *iobase; 121 int err; 122 123 iobase = ioremap_nocache(base, lim); 124 if (!iobase) 125 return -ENOMEM; 126 127 err = nvram_find_and_copy(iobase, lim); 128 129 iounmap(iobase); 130 131 return err; 132 } 133 134 static int nvram_init(void) 135 { 136 #ifdef CONFIG_MTD 137 struct mtd_info *mtd; 138 struct nvram_header header; 139 size_t bytes_read; 140 int err; 141 142 mtd = get_mtd_device_nm("nvram"); 143 if (IS_ERR(mtd)) 144 return -ENODEV; 145 146 err = mtd_read(mtd, 0, sizeof(header), &bytes_read, (uint8_t *)&header); 147 if (!err && header.magic == NVRAM_MAGIC && 148 header.len > sizeof(header)) { 149 nvram_len = header.len; 150 if (nvram_len >= NVRAM_SPACE) { 151 pr_err("nvram on flash (%i bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n", 152 header.len, NVRAM_SPACE); 153 nvram_len = NVRAM_SPACE - 1; 154 } 155 156 err = mtd_read(mtd, 0, nvram_len, &nvram_len, 157 (u8 *)nvram_buf); 158 return err; 159 } 160 #endif 161 162 return -ENXIO; 163 } 164 165 int bcm47xx_nvram_getenv(const char *name, char *val, size_t val_len) 166 { 167 char *var, *value, *end, *eq; 168 int err; 169 170 if (!name) 171 return -EINVAL; 172 173 if (!nvram_len) { 174 err = nvram_init(); 175 if (err) 176 return err; 177 } 178 179 /* Look for name=value and return value */ 180 var = &nvram_buf[sizeof(struct nvram_header)]; 181 end = nvram_buf + sizeof(nvram_buf); 182 while (var < end && *var) { 183 eq = strchr(var, '='); 184 if (!eq) 185 break; 186 value = eq + 1; 187 if (eq - var == strlen(name) && 188 strncmp(var, name, eq - var) == 0) 189 return snprintf(val, val_len, "%s", value); 190 var = value + strlen(value) + 1; 191 } 192 return -ENOENT; 193 } 194 EXPORT_SYMBOL(bcm47xx_nvram_getenv); 195 196 int bcm47xx_nvram_gpio_pin(const char *name) 197 { 198 int i, err; 199 char nvram_var[] = "gpioXX"; 200 char buf[NVRAM_MAX_GPIO_VALUE_LEN]; 201 202 /* TODO: Optimize it to don't call getenv so many times */ 203 for (i = 0; i < NVRAM_MAX_GPIO_ENTRIES; i++) { 204 err = snprintf(nvram_var, sizeof(nvram_var), "gpio%i", i); 205 if (err <= 0) 206 continue; 207 err = bcm47xx_nvram_getenv(nvram_var, buf, sizeof(buf)); 208 if (err <= 0) 209 continue; 210 if (!strcmp(name, buf)) 211 return i; 212 } 213 return -ENOENT; 214 } 215 EXPORT_SYMBOL(bcm47xx_nvram_gpio_pin); 216 217 char *bcm47xx_nvram_get_contents(size_t *nvram_size) 218 { 219 int err; 220 char *nvram; 221 222 if (!nvram_len) { 223 err = nvram_init(); 224 if (err) 225 return NULL; 226 } 227 228 *nvram_size = nvram_len - sizeof(struct nvram_header); 229 nvram = vmalloc(*nvram_size); 230 if (!nvram) 231 return NULL; 232 memcpy(nvram, &nvram_buf[sizeof(struct nvram_header)], *nvram_size); 233 234 return nvram; 235 } 236 EXPORT_SYMBOL(bcm47xx_nvram_get_contents); 237 238 MODULE_LICENSE("GPL v2"); 239